This invention relates generally to motor controller circuits, and, more particularly, to a reconfigurable two-chip set motor controller.
Referring now to FIG. 1, a typical voice control motor (VCM) 16 is driven in a linear current mode in prior art motor controller configuration 10. Driver circuit 12 includes a first amplifier 18, a second amplifier 24, and a sense amplifier 22. The current, Im, driven into motor 16 is proportional to the control voltage, Vcmd, applied at circuit node 14. In the steady state, the motor current, Im, is given by the following equation:
Im=(R2/R1)xc3x97(Vcmd/(Rsxc3x97As))
where resistors R1, R2, and Rs are external to the driver circuit 12 and can be modified as required for a desired current gain for a specific application. The first amplifier 18 is used as an error amplifier, while the second amplifier 24 is used as a fixed gain stage. The control or command voltage Vcmd can be any value within a specified range and the commanded or motor current, Im, will be given by the above equation. System 10 shown above in FIG. 1 is therefore continuous.
Referring now to FIG. 2, a compensated system 20 includes an external compensation circuit 26 to make the system stable. Compensation circuit is typically a simple passive circuit like a combination of a resistor and capacitor or other passive elements.
The driver circuit configurations 10 and 20 shown in FIGS. 1 and 2 are typical for driving a VCM and the circuit elements must be changed to provide different operating modes, such as a pulsed mode of operation. While the circuit configurations 10 and 20 are simple and provide a stable operating system, it is inconvenient to change circuit elements to provide additional operating modes and restricts system versatility to adapt to changing load conditions.
What is desired, therefore, is a motor controller architecture that is easily reconfigurable for use in several operating modes and able to work in conjunction with a wide variety of controller circuits.
It is, therefore, a principal object of the present invention to provide a multi-mode motor controller architecture that is easily reconfigurable to operate in several modes and able to work in conjunction with a wide variety of controller circuits.
It is an advantage of the present invention that the motor can be driven in different modes without a need to change the circuit elements.
It is a further advantage of the present that new modes of operation can be evaluated or used in addition to established, conventional modes of operation.
According to the present invention a multi-mode motor controller architecture includes a motor, an integrated circuit controller, and an integrated circuit driver circuit. The integrated circuit controller includes a pulse generator, a DAC, an ADC, and a digital compensator circuit. The integrated circuit driver circuit is in communication with the controller and includes an error amplifier, first and second output amplifiers for driving the motor, and a sense amplifier. The motor controller architecture is configurable to operate in a linear mode, a pulsed mode, or a switchable linear/pulsed mode. The controller architecture can be implemented with external compensation circuitry, such as a resistor-capacitor circuit, or with the digital compensation circuitry located within the controller integrated circuit.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention which proceeds with reference to the accompanying drawings.